C++ QueuedRequest::processRequest方法代码示例

S32 LLQueuedThread::processNextRequest()
{
	QueuedRequest *req;
	// Get next request from pool
	lockData();
	while(1)
	{
		req = NULL;
		if (mRequestQueue.empty())
		{
			break;
		}
		req = *mRequestQueue.begin();
		mRequestQueue.erase(mRequestQueue.begin());
		if ((req->getFlags() & FLAG_ABORT) || (mStatus == QUITTING))
		{
			req->setStatus(STATUS_ABORTED);
			// Unlock, because we can't call finishRequest() while keeping this lock:
			// generateHandle() takes this lock too and is called while holding a lock
			// (ie LLTextureFetchWorker::mWorkMutex) that finishRequest will lock too,
			// causing a dead lock.
			// Although a complete rewrite of LLQueuedThread is in order because it's
			// far from robust the way it handles it's locking; the following rationale
			// at least makes plausible that releasing the lock here SHOULD work if
			// the original coder didn't completely fuck up: if before the QueuedRequest
			// req was only accessed while keeping the lock, then it still should
			// never happen that another thread is waiting for this lock in order to
			// access the QueuedRequest: a few lines lower we delete it.
			// In other words, if directly after releasing this lock another thread
			// would access req, then that can only happen by finding it again in
			// either mRequestQueue or mRequestHash. We already deleted it from the
			// first, so this access would have to happen by finding it in mRequestHash.
			// Such access happens in the following functions:
			// 1) LLQueuedThread::shutdown -- but it does that anyway, as it doesn't use any locking.
			// 2) LLQueuedThread::generateHandle -- might skip our handle while before it would block until we deleted it. Skipping it is actually better.
			// 3) LLQueuedThread::waitForResult -- this now doesn't touch the req when it has the flag FLAG_LOCKED set.
			// 4) LLQueuedThread::getRequest -- whereever this is used, FLAG_LOCKED is tested before using the req.
			// 5) LLQueuedThread::getRequestStatus -- this is a read-only operation on the status, which should never be changed from finishRequest().
			// 6) LLQueuedThread::abortRequest -- it doesn't seem to hurt to add flags (if this happens at all), while calling finishRequest().
			// 7) LLQueuedThread::setFlags -- same.
			// 8) LLQueuedThread::setPriority -- doesn't access req with status STATUS_ABORTED, STATUS_COMPLETE or STATUS_INPROGRESS.
			// 9) LLQueuedThread::completeRequest -- now sets FLAG_AUTO_COMPLETE instead of deleting the req, if FLAG_LOCKED is set, so that deletion happens here when finishRequest returns.
			req->setFlags(FLAG_LOCKED);
			unlockData();
			req->finishRequest(false);
			lockData();
			req->resetFlags(FLAG_LOCKED);
			if ((req->getFlags() & FLAG_AUTO_COMPLETE))
			{
				req->resetFlags(FLAG_AUTO_COMPLETE);
				mRequestHash.erase(req);
// 				check();
				unlockData();
				req->deleteRequest();
				lockData();
			}
			continue;
		}
		llassert_always(req->getStatus() == STATUS_QUEUED);
		break;
	}
	U32 start_priority = 0 ;
	if (req)
	{
		req->setStatus(STATUS_INPROGRESS);
		start_priority = req->getPriority();
	}
	unlockData();

	// This is the only place we will call req->setStatus() after
	// it has initially been seet to STATUS_QUEUED, so it is
	// safe to access req.
	if (req)
	{
		// process request
		bool complete = req->processRequest();

		if (complete)
		{
			lockData();
			req->setStatus(STATUS_COMPLETE);
			req->setFlags(FLAG_LOCKED);
			unlockData();
			req->finishRequest(true);
			if ((req->getFlags() & FLAG_AUTO_COMPLETE))
			{
				lockData();
				req->resetFlags(FLAG_AUTO_COMPLETE);
				mRequestHash.erase(req);
// 				check();
				req->resetFlags(FLAG_LOCKED);
				unlockData();
				req->deleteRequest();
			}
			else
			{
				req->resetFlags(FLAG_LOCKED);
			}
		}
		else
//.........这里部分代码省略.........